Tuning apparatus



April 1937- c. A. GUNTHER TUNING APPARATUS Filed Oct. 51 1954 2Sheets-Sheet 1 76 QQ m Patented Apr. 27, 1937 TUNING APPARATUS ClarenceA. Gunther, Haddonfield, N. 1., assignor to General Electric Company, acorporation of New York Application October 31, 1934, Serial No. 150,811

10 Claims. (01.250-40) My invention relates to improvements in tuningapparatus for radio receivers and the like.

For the purpose of tuning over a wide frequency range in radioreception, sets of transformer coils and associated trimming condensersare usually provided for the tuned circuits, each set being designed tocover a given frequency band in the entire range. The different sets oftuning coils and trimming condensers are connected in circuitselectively by a wave-change switch.

One of the objects of my invention is to provide improved tuningapparatus for a radio receiver of the character referred to in which thetuning coils and condensers are so mounted and disposed with respect toeach other that a change from one frequency band to another can be madeeasily and quickly, and in which provision is made for shielding thedifferent groups of tuning elements from each other.

Another object of my invention is to provide improved tuning apparatusfor a radio receiver of the character referred to which is relativelysimple in construction and in its manner of operation, and in whichadjustments can be made easily while the receiver is in operation.

Other objects and advantages will hereinafter appear.

In accordance with my invention, a group of antenna coils and aplurality of groups of coils for the radio frequency stages are disposedin separate compartments about a common axis, and are rotated togetherin changing from one band to another. A set of fixed contactsengagessuccessively with complementary contacts connected to the tuningelements, whereby the proper element of each group is placed in circuitfor reception over the selected band of the entire frequency range.

The antenna coils are normally out of inductive relation with respect tothe tuning coils of the first radio frequency stage, the particularantenna coil needed for reception over a given band being swimg intooperating position after the required movement of all the parts has beenmade.

My invention resides in the improved construction of the characterhereinafter described and claimed. For the purpose of illustrating myinvention, an embodiment thereof is shown in the drawings, whereinFigure l is an elevational view, partly in section, of tuning apparatusconstructed and operating in accordance with my invention, some of theparts being removed for the sake of clearness;

Fig.2 is a sectional view, the section beins taken on the line 2-2 inFig. 1;

Fig. 3 is a perspective view of a wrench used in making adjustments inmy improved apparatus;

Fig. 4 is a sectional view, the section being taken on the line l4 inFig. 1;

Fig. 5 is a sectional view, the section being taken on the line 5-5 inFig. 4; and.

Fig. 6 is an enlarged sectional view, the section being taken on theline 6--8 in Fig. 5.

,In the drawings, the reference numeral ll designates a shaft journaledat its ends in bearings l2 and I4, and on which are fixed members i6, i8and 20 for supporting the tuning coils and condensers.

The member i0 is comprised of circular end walls'22 and 24 andpartitions 26 between the latter to form compartments 28. The partitions26 extend radially outwardly from a central bearing portion 21 throughwhich the shaft l0 extends. The members is and 20 are of the sameconstruction.

The apparatus is enclosed in a casing 30 provided with shieldingpartitions 32, 34, I0 and II to form compartments 0, 42, 44 and 4|.

The tuning apparatus disclosed by way of example is for use in a radioreceiver in which eight frequency bands are used to cover a frequencyrange of 1,000 to 30,000 kilocycles. Any other range, naturally, couldbe covered by properly designing the inductors and trimmers. Eightantenna coils 48, one for each band, are disposed in the compartment 40.Eight transformer coils 50, for the first radio frequency stage, arecarried by the rotary member or drum i6. Eight transformer coils, forthe second radio frequency stage, are carried by the member II, andeight transformer coils 52, for the third radio frequency stage, arecarried by the member 20.

Each of the coils 52 is mounted on a bracket 54 which is fixed by screws56 to a base plate 5|. A trimmer or so-called lining-up condenser Oil issecured to the bracket 54 and is connected in circuit with the coil 52,as represented. This condenser is of the air type, adjustable andselflocking. The end of the shaft 62 to which the rotor plates are fixedis notched and extends through an opening 84 in the adjacent end wall ofthe member 20. The base plate 58 is screwed into place, as shown, forwhich purpose the edges of the end walls of the member 20 are tapped.The coil 52, the condenser 00, the base plate 58,

and the associated bracket 54 comprise a unit disposed within one of thechambers of the member 20. The unit is provided with contacts 65 whichextend radially outwardly and engage with complementary fixed contacts68 secured to a casing I containing other parts of the receiver, such asa gang condenser (not shown), with which the coil 52 and the condenser60 are to be connected. Similar units are disposed in each of the otherseven chambers of the member 20. The base plates 58 of these units closethese chambers, and form with the member 20 a cylindrical drum.

The coils associated with the members I6 and I0 form part of units whichare similar to those just described, and which are disposed,respectively, in the compartments of these members. The units associatedwith the member I0 are provided with contacts 12 which engage with fixedcontacts 14, and the units associated with the member I8 are providedwith contacts which engage with fixed contacts I8.

The antenna coils 48 are pivotally mounted, as represented, to the edgeof a. plate 80 fixed to the shaft I 0. By means of springs 02, the coils48 are biased to the position in which their axes 83 are perpendicularto the shaft I0. In this position, there is no coupling between theantenna coils 48 and the tuning coils 50 in the adjacent compartment 42.

In operation, a tuning unit of each of the three groups of units isconnected in circuit, and the antenna coil for the particular frequencyband selected is in position with its axis 831; parallel to the shaftI0, as shown in Fig. 1, so that this coil is inductively coupled to theadjacent coil 50 whose axis is also parallel to the shaft Ill. Theantenna coil is held in operating position by a cam 84 fixed on a shaft00 which engages a pin 88 extending outwardly from the antenna coil, asmore clearly shown in Fig. 5. In tuning for reception over the nextfrequency band, the operator rotates the shaft 88 in a counter-clockwisedirection, as viewed in Fig. 4, to permit the antenna coil to swingback, under the action of the spring 02, to the position in which itsaxis is perpendicular to the shaft III. In doing this, the shaft 86 mustbe turned through 180 to the position in which a pin 90, fixed to thisshaft, is adjacent a slot 92 in the bearing member 94. The shaft 06 canthen be pulled outwardly to the right, as viewed in Fig. 5, to compressa spring 96 and withdraw the end of the shaft from an indexing hole 90in the face of the plate 00. The shaft I0 can then be rotated by turninga crank I00 connected to the shaft through gears I02 and I04. When thenext set of tuning elements is in position, the spring 96 causes the endof the shaft 86 to snap into the next indexing hole in the plate 80. Theshaft 86 is then rotated in a clockwise direction through 180 to swingthe antenna coil into the correct position, with its axis parallel tothe shaft I0. When it is desired to tune through more than one frequencyband, the shaft 86 is held out until the shaft I0 has been rotated tobring the required set of tuning units into operating position.

An index plate I05 fixed to the end of the shaft I0 provides anindication of the frequency band for which the apparatus is adjusted.

A switch I06 is arranged as shown diagrammatically in Fig. 5, to beclosed and short-circuit the head-phones I01 when the shaft 00 is pulledout. In this way, excessive noise is prevented when shifting from oneband to anoth.

The antenna coils are connected in circuit y contacts I00 carried by thegear I04 and whi h engage with fixed contacts H0.

The end wall 22 of the member I0 is provided with openings 2 adjacentthe coils 00 so that this wall does not shield the latter from theantenna coils 40. The portion of the shield 32, adjacent the holes II2may also be cut away or made of a reticulated screen material or thelike which will not interfere with the inductive coupling.

When any given set of tuning units is in working position, the trimmingcondensers can be adjusted. For example, if it is desired to adjust theoperating condenser 60, a wrench II4, shown in Fig. 3, is insertedbetween the partition 30 and the adjacent end wall of the member toposition a blade H6 with which it is provided in the notched end of thecondenser shaft 02. The cup-like head Ill fits over the end of the shaft62, and operates to hold the wrench in place, while the shaft is turnedto make the desired adjustment of the condenser.

Since there are eight sets of tuning units to cover as many differentfrequency bands over the entire operating range, it is proposed thatthere be an eight to one reduction between the gears I02 and I04. Inthis way, it is provided that a change to the next frequency band ismade by one complete turn of the crank I00.

From the foregoing it will be seen that I have provided improved tuningapparatus which comprises a plurality of tuning elements or unitssupported about a common axis and in individual groups disposed alongthis axis, the elements of each group being shielded from each other bythe partitions 26. It will also be seen that on account of theinterlocking action of the pin 90 and the slot 92, and the entry of theend of shaft 06 in the indexing holes 00, the shaft I0 cannot be rotateduntil the shaft 00 has been rotated to permit the antenna coil to swingback out of operating position under the action of the biasing spring02.

While but one embodiment of my invention has been shown, it will beunderstood that various modifications, within the conception of thoseskilled in the art, are possible without departing from the spirit of myinvention or the scope of the claims.

I claim as my invention:

1. Tuning apparatus comprising a plurality of tuning elements, meanssupporting 'said elements about a common axis and for movement todifferent angular positions with respect to said axis, contact meansassociated respectively with said elements, means common with respect tosaid elements and cooperable with said contact means for connecting saidelements in circuit, means supporting said first and third named meansfor rotary movement relatively with respect to each other whereby saidunits can be connected in circuit selectively, and means for changingthe angular position of the connected element with respect to said axis.

2. In a radio receiver, a first group of coils, a second group of coils,means supporting the coils of each group about a common axis with saidgroups disposed along said axis and with the coils of the first groupnormally disposed with their axes substantially perpendicular to thecommon axis and with the coils of the second group disposed with theiraxes substantially parallel to the common axis, contact means forconnecting simultaneously adjacent coils of said groups in circuit, andmeans for moving the connected coil of the first group into positionwith its axis substantially parallel to the common axis.

3. A coupling unit for a structure herein described, comprising ashielding casing, a plurality of separate circuit units mounted aroundthe inner periphery of thecasing, said circuit unitsineludingimpedances, contacts carried by said units connected to \said impedancesand extendin through the casing, fixed contacts connected to thecircuit, exterior ofthe casing but adapted to be engaged by the contactsextending through said casing as the same is rotated, and means forrotating the casing.

4. A coupling unit for a structure herein described, comprising ashielding casing; a plurality of separate circuit units mounted aroundthe inner periphery of the casing, said circuit units includingimpedances, each of said circuit units comprising an insulator having abase portion and a stem, said base portion fitting the inner part of thecasing and having switch contacts extending through the casing, saidstem carrying at least one impedance connected to said switch contactsfor the purpose described.

5. A coupling unit for a structure herein described, comprising ashielding casing, a plurality of separate circuit units mounted aroundthe innerfperiphery of the casing, said circuit units includingimpedances, each of said circuit units comprising an insulator having abase portion and a stem, said base portion fitting the inner part of thecasing and having switch contacts extending through the casing, saidstem carrying at least one impedance connected to said switch contactsfor the purpose described, characterized in that the stems of saidinsulators are positioned and arranged so as to be on lines extending tothe axis of the casing.

6. A combination structure for the purpose described, including aplurality of separable coupling units, each composed of a plurality ofsimilarly constructed circuit units including impedances having suitableelectrical values for responding to electrical impulses of differentfrequencies, said coupling units being shielded one from the other andarranged so the impedances for the same frequency band for all'thecircuits arecin accurate alignment around the axis of the structure,switch contacts connected to said impedances, means for rotating all ofsaid coupling units and switch contacts together, and stationarycontacts connected to the various circuits adapted to be engaged by saidrotatable contacts.

7. In a device of the class described, a plurality of individual metalcontainers fixed on a common shaft for simultaneous rotation, aplurality of shielded compartments in said containers, a plurality ofsets of tuning units in said compartments, the units constituting eachset. being mounted in corresponding compartments in the severalcontainers, terminals projecting from said compartments and individualto the tuning units therein, fixed contacts common to all of theterminals of a given container, and means for rotating said shaft tosimultaneously connect all of the tuning units in a given setto saidcontacts.

8. In a device of the class described, a rotatable carrier, meansdividing said carrier into shielding compartments, removable covers forsaid compartments, and tuning elements carried by said covers.

9; In' a device of the class described, a rotatable metal drum, meansdividing said drum into shielding compartments, tuning elements in saidcompartments and removable peripheral covers for said compartments.

10. The invention as set forth in claim 9 wherein said tuning elementsare carried by said removable peripheral covers.

CLARENCE A. GUN'I'HER.

